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[Bug win32/12716] New: addresses of exported symbols of a DLL shouldbe looked up by ordinal
- From: "pebolle at tiscali dot nl" <sourceware-bugzilla at sourceware dot org>
- To: gdb-prs at sourceware dot org
- Date: Fri, 29 Apr 2011 19:19:48 +0000
- Subject: [Bug win32/12716] New: addresses of exported symbols of a DLL shouldbe looked up by ordinal
- Auto-submitted: auto-generated
http://sourceware.org/bugzilla/show_bug.cgi?id=12716
Summary: addresses of exported symbols of a DLL should be
looked up by ordinal
Product: gdb
Version: 7.2
Status: NEW
Severity: normal
Priority: P2
Component: win32
AssignedTo: unassigned@sourceware.org
ReportedBy: pebolle@tiscali.nl
0) I ran into a PE32 DLL that exports a number of symbols. objdump shows it
uses an "Export Address Table", a "Name Pointer Table" and an "Ordinal Table".
1) If you look at objdump's dump of the EA table and the "[Ordinal/Name
Pointer] Table" one sees that the O/NP table is (basically) unsorted: it's
neither sorted on ordinal nor (alphabetically) on the symbols. BUT (the version
of) gdb (that I use) looks up the address of a symbol in the O/NP table as if
that tables has the same order as the EA table. But what gdb actually should do
is: look up a symbol in the O/NP table, get its ordinal and look up an address
in the EA table using that ordinal.
2) I just happened to use gdb with a couple of symbols (which, as I knew from
wine's debugging output, were really used) that gdb mapped to addresses that
simply were not used at all in the code paths I apparently ran. This confusing
behaviour quickly made me think that gdb never set pending breakpoints in that
DLL (which I knew as loaded at runtime through LoadLibraryA). Hence the feeling
I ran into the issue reported in bug #9474.
3) A (still untested) patch for this issue:
diff --git a/gdb/coff-pe-read.c b/gdb/coff-pe-read.c
index ca87b72..0483158 100644
--- a/gdb/coff-pe-read.c
+++ b/gdb/coff-pe-read.c
@@ -150,6 +150,14 @@ read_pe_truncate_name (char *dll_name)
}
}
+static unsigned int
+pe_as16 (void *ptr)
+{
+ unsigned char *b = ptr;
+
+ return b[0] + (b[1] << 8);
+}
+
/* Low-level support functions, direct from the ld module pe-dll.c. */
static unsigned int
pe_get16 (bfd *abfd, int where)
@@ -309,11 +317,11 @@ read_pe_exported_syms (struct objfile *objfile)
bfd_bread (expdata, (bfd_size_type) export_size, dll);
erva = expdata - export_rva;
+ ordbase = pe_as32 (expdata + 16); /* unused */
nexp = pe_as32 (expdata + 24);
+ exp_funcbase = pe_as32 (expdata + 28);
name_rvas = pe_as32 (expdata + 32);
ordinals = pe_as32 (expdata + 36);
- ordbase = pe_as32 (expdata + 16);
- exp_funcbase = pe_as32 (expdata + 28);
/* Use internal dll name instead of full pathname. */
dll_name = pe_as32 (expdata + 12) + erva;
@@ -339,8 +347,10 @@ read_pe_exported_syms (struct objfile *objfile)
/* Pointer to the names vector. */
unsigned long name_rva = pe_as32 (erva + name_rvas + i * 4);
+ unsigned long ordinal = pe_as16 (erva + ordinals + i * 2);
+
/* Pointer to the function address vector. */
- unsigned long func_rva = pe_as32 (erva + exp_funcbase + i * 4);
+ unsigned long func_rva = pe_as32 (erva + exp_funcbase + ordinal * 4);
/* Find this symbol's section in our own array. */
int sectix = 0;
--
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